[Merge] ~juliank/grub/+git/ubuntu:ubuntu into ~ubuntu-core-dev/grub/+git/ubuntu:ubuntu

[Julian Andres Klode]

Updated:

- moved the ZFS changes into the original ZFS patch
- fix unset variable errror if GRUB_FLAVOUR_ORDER is undefined
- Add version_test_gt to {a,b}_preferred variable names for scoping purposes

Still need to move the gettext bases in the base branch and rebase on that so they get preserved.
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https://code.launchpad.net/~juliank/grub/+git/ubuntu/+merge/385358
Your team Ubuntu Core Development Team is requested to review the proposed merge of ~juliank/grub/+git/ubuntu:ubuntu into ~ubuntu-core-dev/grub/+git/ubuntu:ubuntu.